Chapter 8: Problem 4
Is a system of linear equations with at least one solution consistent or inconsistent?
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These are the key concepts you need to understand to accurately answer the question.
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Chapter 8: Problem 4
Is a system of linear equations with at least one solution consistent or inconsistent?
These are the key concepts you need to understand to accurately answer the question.
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Use an inverse matrix to solve (if possible) the system of linear equations. $$\left\\{\begin{array}{l} 4 x-2 y+3 z=-2 \\ 2 x+2 y+5 z=16 \\ 8 x-5 y-2 z=4 \end{array}\right.$$
Sales The projected sales \(S\) (in millions of dollars) of two clothing retailers from 2015 through 2020 can be modeled by \(\left\\{\begin{array}{ll}S-149.9 t=415.5 & \text { Retailer } \mathrm{A} \\\ S-183.1 t=117.3 & \text { Retailer } \mathrm{B}\end{array}\right.\) where \(t\) is the year, with \(t=5\) corresponding to 2015 (a) Solve the system of equations using the method of your choice. Explain why you chose that method. (b) Interpret the meaning of the solution in the context of the problem. (c) Interpret the meaning of the coefficient of the \(t\) -term in each model. (d) Suppose the coefficients of \(t\) were equal and the models remained the same otherwise. How would this affect your answers in parts (a) and (b)?
Write the matrix in row-echelon form. Remember that the row-echelon form of a matrix is not unique. $$\left[\begin{array}{rrrr} 1 & -3 & 0 & -7 \\ -3 & 10 & 1 & 23 \\ 4 & -10 & 2 & -24 \end{array}\right]$$
Write the system of linear equations represented by the augmented matrix. Then use back-substitution to find the solution. (Use the variables \(x, y,\) and \(z,\) if applicable.) $$\left[\begin{array}{llll} 1 & 8 & \vdots & 12 \\ 0 & 1 & \vdots & 3 \end{array}\right]$$
Determine whether the matrix is in row-echelon form. If it is, determine if it is also in reduced row-echelon form. $$\left[\begin{array}{llll} 1 & 3 & 0 & 0 \\ 0 & 0 & 1 & 8 \\ 0 & 0 & 0 & 0 \end{array}\right]$$
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